KR20010029131A - Optical pickup apparatus - Google Patents

Abstract

PURPOSE: An optical pick-up device is provided to detect a relative slop between the recording media and an object lens without additional tilt sensor, therefore, reducing the number of components. CONSTITUTION: A light source(35) generates light to radiate the light. An optical path converter(50) converts a processing path of an incident light. An object lens(70) focuses the incident light on a recording media(30). A main optical detector(81) is reflected from a record surface of the recording media(30), and receives the incident light via the object lens(70) and the optical path converter(50) to detect an information signal and an error signal. An object lens location detector detects a moving capacity of the object lens(70). A slope detector calculates a signal receiving the reflected light and a signal inputted from the object lens location detector, and detects a relative slope for the object lens(70) of the recording media(30). A slope optical detector(83) is reflected from the protecting layer surface to receive the incident light via the object lens(70) and the optical path converter(50), and has many dividing boards that perform a photoelectric conversion and are arranged to a tangential and a semidiameter direction of the recording media(30). A slop detecting circuit(100) receives detection signals of each dividing board and an object lens location signal, and detects a slope of the recording media(30) compensated an off-set according to a movement of the object lens(70).

Description

Optical pickup apparatus

The present invention relates to an optical pickup device, and more particularly, to an optical pickup device capable of detecting a relative inclination between an objective lens and a recording medium.

In general, an optical pickup apparatus records / reproduces an information signal while moving in a radial direction of a recording medium such as a rotating disk mounted on a turntable, and deterioration of the recording / reproducing signal occurs when the rotating disk is inclined due to eccentricity. Occurs.

In particular, in the case of an optical pickup apparatus employing a light source that emits shorter wavelength light and an objective lens having a larger numerical aperture in order to increase the recording density, the coma aberration is largely generated due to the inclination of the disc, resulting in deterioration of the recording / reproduction signal. Becomes more serious.

In order to prevent such deterioration of the recording / reproducing signal by detecting the inclination amount of the disc and correcting the inclination, a device for detecting the relative inclination between the disc and the objective lens as shown in FIG. 1 has been proposed. There is a bar.

Referring to FIG. 1, the holder 10 supporting the objective lens 3 is provided to be movable on the main body 20. A first tilt sensor is provided on the outer side facing the disk 1 of the upper wall 22 of the main body 20, and a second tilt sensor is provided on the inner side of the upper wall 22. In addition, a reflector 17 is provided on an upper surface of the holder 10 facing the second tilt sensor. Here, the holder 10 has a coil member (not shown) around the main body 20 to actuate the objective lens 3 fixed thereon by interaction with the permanent magnet 21 installed on one side wall of the main body 20. Is installed. Meanwhile, although FIG. 1 illustrates that the upper wall 22 is integrated with the main body 20, a cover member (not shown) is generally provided instead of the integrated upper wall 22.

The first tilt sensor includes a light emitting diode 11 and a pair of photodiodes 13 and 12 disposed on both sides of the light emitting diode 11 along a radial direction. Light emitted from the light emitting diodes 11 is reflected from the surface of the disk 1 and received by the photodiodes 12 and 13. The detected light amounts of the photodiodes 12 and 13 are the same when the disk 1 is not inclined with respect to the main body 20, and is different from each other when the disk 1 is inclined.

Similarly, the second tilt sensor includes a light emitting diode 14 and a pair of photodiodes 15 and 16 arranged on both sides of the light emitting diode 14 along the radial direction. The light emitted from the light emitting diodes 14 is incident and reflected on the reflecting plate 17 provided on the upper surface of the holder 10 and then received by the photodiodes 15 and 16. The amount of light detected by the photodiodes 15 and 16 is the same when the holder 10 is not inclined with respect to the main body 20, that is, when the objective lens 3 is not inclined. ) Is different when tilted.

In the first and second tilt sensors as described above, the detection signals of the photodiodes 13, 15 and the photodiodes 12, 16 are input to the + and − input terminals of the differential amplifier 18 and differentially operated. .

Therefore, as shown in FIG. 2A, when the disk 1 and the objective lens 3 are not inclined, the detection signals of the photodiodes 12 and 13 are the same and the photodiodes 15 and 16 are separated. Since the detection signals are identical to each other, the output signal value of the differential amplifier 18 becomes zero, which means that there is no relative inclination between the disk 1 and the objective lens holder 10.

As shown in FIG. 2B, the amount of light detected by one photodiode 12 when the disk 1 is inclined with respect to the main body 20 and the holder 10 is not inclined with respect to the main body 20. Increases, while the amount of light detected in the other photodiode 13 decreases. In addition, the detected light amounts of the photodiodes 15 and 16 are the same.

In this case, the differential signal of the differential amplifier 18 becomes a positive value according to the difference between the two photodiodes 12 and 13.

Therefore, in order to correct the inclination of the disk 1, as shown in FIG. 2C, when the holder 10 is inclined to have the same inclination in the same direction as the inclination of the disk 1, the photo of the first tilt sensor The detection amounts of the diodes 12 and 13 are different from each other, and at the same time, the detection amounts of the photodiodes 15 and 16 of the second tilt sensor are also different from each other. However, the differential signal of the differential amplifier 18 becomes zero, which means that the inclination of the disc 1 is corrected so that there is no relative inclination between the disc 1 and the objective lens 3.

As described above, the conventional disk tilt detection device detects the inclination of the disk 1 and the holder 10 with respect to the main body 20, and mounts them on the holder 10 in the same manner as the inclination amount of the disk 1. By tilting the objective lens 3 with respect to the main body 20, the relative inclination of the disk 1 with respect to the objective lens 3 can be corrected.

However, the conventional disk tilt detection device as described above requires two or more tilt sensors to be installed separately from the optical pickup device, so that the number of parts is high and thus the manufacturing cost is high, and the reflector plate 17 is installed in the holder 10. There is a disadvantage in that the actuation performance of the optical pickup device is lowered due to an increase in the loading load.

In addition, accurate tilt detection is difficult due to the offset generated by the movement of the objective lens 3 during tracking.

The present invention has been devised in view of the above-mentioned point, and it is possible to detect a relative inclination between the objective lens and the recording medium without a separate tilt sensor, and to prevent an offset due to the movement of the objective lens in the inclination detection signal. It is an object of the present invention to provide an optical pickup device.

1 is a perspective view schematically showing the configuration of a conventional disk tilt detection device;

2A to 2C are cross-sectional views schematically illustrating a process of detecting and correcting a disk tilt in a conventional disk tilt detection apparatus;

3 is a view schematically showing the configuration of an optical pickup device according to an embodiment of the present invention;

4 is a plan view schematically showing the configuration of the main part of FIG.

5 is a plan view schematically showing another embodiment of the objective lens position detection means of FIG.

6 is a plan view showing an embodiment of the hologram lens of FIG.

7 is a view showing a light spot received by the tilt photodetector of FIG.

8A and 8B show light spots received by the tilt photodetector of FIG. 4 when the tilt is generated on the recording medium and when the tilt is corrected.

9 is a schematic view showing the configuration of an optical pickup apparatus according to another embodiment of the present invention;

10 is a plan view schematically showing the configuration of the main part of FIG.

11 is a view showing a light spot received by the photodetector of FIG.

12 is a view schematically showing the configuration of an optical pickup apparatus according to another embodiment of the present invention;

13 is a plan view schematically showing the configuration of the main part of FIG.

FIG. 14 is a sectional view showing another embodiment of the recording medium employed in FIG. 12; FIG.

<Description of the code | symbol about the principal part of drawing>

30,300 ... Recording medium 31,301 ... Recording surface

33,303 ... Protective layer 33a, 303a ... Protective layer surface

40 ... hologram lens 41, 43 ... first and second transmission

50.Light path conversion means 70 ... Objective lens

81,181 ... main photodetector 83,283,284,285,286 ... incline photodetector

90 ... flag sensor 100,200,400 ... inclined detection circuit

110,210 ... Operator 120,220 ... Operator

160 ... collimating lens 305 ... color separation layer

311,321 ... First and second light sources 313,323 ... Second and third light path converting means

315,325 ... first and second photodetectors 320 ... optical modules

340 ... First optical path changing means

In order to achieve the above object, the present invention provides an optical pickup apparatus for recording and reproducing an information signal of a recording medium having a recording surface on which an information signal is recorded and a protective layer for protecting the recording surface on a side to which light of the recording surface is incident. A light source for generating and emitting light; Optical path converting means for converting a traveling path of the incident light; An objective lens for focusing light incident from the light source toward a recording medium; A main photodetector, which is reflected from the recording surface of the recording medium and receives the light incident through the objective lens and the optical path converting means to detect an information signal and / or an error signal; Objective lens position detecting means for detecting a movement amount of the objective lens; And calculating the signal received from the light source and reflected from the surface of the protective layer of the recording medium and the signal input from the objective lens position detecting means to correct the offset according to the movement of the objective lens. And inclination detecting means for detecting an inclination relative to the lens.

Here, the inclination detecting means receives a light reflected from the surface of the protective layer and received through the objective lens and the optical path converting means, and each of the plurality of dividers independently photoelectrically converts into a tangential direction of the recording medium and A gradient photodetector disposed in a radial direction; And an inclination detection circuit unit configured to detect an inclination of the recording medium in which an offset according to the movement of the objective lens is corrected by receiving the detection signal of each partition plate of the inclination light detector and the objective lens position signal of the objective lens position detecting means. do.

According to a feature of the invention, the inclination detecting means is disposed on an optical path between the light source and the optical path converting means, so that the light incident from the light source side is increased to increase the amount of light reflected from the surface of the recording medium protective layer. It is preferable to further provide a hologram lens for selectively diffraction transmission.

In addition, the inclined photodetector is located on one side of the main photodetector, the partition line is divided into four partition plates arranged in a counterclockwise direction having a 2 × 2 matrix arrangement parallel to the tangential direction and the radial direction of the recording medium ( a, b, c, d, wherein the inclination detection circuit part is differentially inputted with the detection signals of the partition plates a and d and the detection signals of the partition plates b and c at different input terminals. A first operator configured to input the objective lens position signal to the one input terminal and output a radial inclination signal in which an offset according to the movement of the objective lens is corrected; And a second operator configured to differentially detect the detection signals of the partition plates a and b and the detection signals of the partition plates c and d to output a tangential signal in a tangential direction.

According to another feature of the invention, the inclined photodetector, a plurality of partition plates disposed in the tangential and / or radial direction of the recording medium on at least one side of the main photodetector to detect light reflected from the surface of the protective layer It is provided.

On the other hand, the objective lens position detecting means may be provided with a flag sensor for detecting the movement amount of the objective lens.

Alternatively, the main photodetector includes first and second light receiving regions each independently photoelectrically converting at a predetermined angle with respect to the radial direction of the recording medium with respect to the optical axis to the objective lens position detecting means. And a differential operator configured to detect the center error signal by differentially detecting the detection signals of the first and second light receiving regions.

On the other hand, the present invention provides an optical pickup apparatus for recording and reproducing an information signal of a recording medium having a recording surface on which an information signal is recorded and a protective layer for protecting the recording surface on a side on which light of the recording surface is incident. First and second light sources that emit; First light path converting means for directing the light emitted from the first and second light sources to the recording medium; An objective lens for focusing incident light toward the recording medium; Second optical path converting means disposed on an optical path between the first light source and the first optical path converting means and converting a traveling path of incident light; A first photodetector configured to receive light reflected from the recording medium and converted by the second optical path converting means; Third optical path converting means disposed on an optical path between the second light source and the first optical path converting means to convert a traveling path of the incident light; A second photodetector configured to receive light reflected from the recording medium and converted by the third optical path converting means; Objective lens position detecting means for detecting a movement amount of the objective lens; And receiving the detection signal of the first or second photodetector and the objective lens position signal of the objective lens position detecting means to receive light emitted from the first or second light source and reflected from the surface of the protective layer of the recording medium. And an inclination detection circuit unit for detecting an inclination of the recording medium in which the offset according to the movement of the objective lens is selectively corrected.

Here, one light source among the first and second light sources irradiates light on the recording surface of the recording medium to record and reproduce the information signal on the recording surface, and another light source irradiates light on the surface of the protective layer of the recording medium to protect the protective layer. The light reflected from the surface may be detected by a photodetector corresponding thereto to detect the inclination of the recording medium.

On the other hand, the first light source generates and outputs light suitable for recording and / or playing HD-DVD, and the second light source generates and outputs light suitable for recording and / or playing DVD. It is preferable that it is provided so that compatibility may be adopted.

In this case, the first and second light sources are reflected on the surface of the protective layer of the DVD or HD-DVD and received by the first or second photodetector to selectively input the detected signal to the inclination detection circuit. Detect the tilt of the DVD.

Here, it is preferable that the first and second light sources generate and emit light in different wavelength regions.

The first or second photodetector comprises four partition plates (a, b, c, d) whose boundaries are arranged counterclockwise with a 2x2 matrix arrangement parallel to the tangential and radial directions of the recording medium. Wherein the inclination detection circuit part is differentially inputted with a detection signal of the partition plates a and d and a detection signal of the partition plates b and c different from each other, and is positioned at the one input terminal. A first operator for inputting a signal and outputting a radial inclination signal in which an offset according to the movement of the objective lens is corrected; And a second operator configured to differentially detect the detection signals of the partition plates a and b and the detection signals of the partition plates c and d to output a tangent inclination signal.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. 3, 9 and 12, the optical pickup apparatus according to the present invention protects the recording surface 31 on which the information signal is recorded and the recording surface 31 on the side where light from the recording surface 31 is incident. It is characterized in that the information signal of the recording medium 30 having the protective layer 33 for recording and reproducing is detected, and the relative inclination with respect to the objective lens of the recording medium 30 can be detected.

Referring to FIG. 3, an optical pickup apparatus according to an exemplary embodiment of the present invention includes a light source 35 for generating and emitting light, an optical path converting means 50 for converting a traveling path of incident light, and a recording medium 30 for incident light. An objective lens 70 for focusing the light, a main photodetector 81 for detecting an information signal and / or an error signal, an objective lens position detecting means for detecting an amount of movement of the objective lens, and an inclination for detecting an inclination of the recording medium 30 It comprises a detection means.

The light source 35 is, for example, a semiconductor laser that generates and emits laser light having an intensity distribution such as a Gaussian distribution. The intensity of the light emitted from the light source 35 is mostly located in the paraxial region. Therefore, the light (indicated by the dotted lines) located in the paraxial region is used to record / reproduce the information signal of the recording medium 30. In addition, circular axis light (indicated by a solid line) around the paraxial region is used to detect an inclination of the recording medium 30, which is typically light because the intensity of the circular axis is much weaker than that of the paraxial region. It is light that is not used in the optical pickup device and is lost. Here, the range of the paraxial region and the circular region is determined relative to each other, the range can be changed as necessary.

The optical path converting means 50 is disposed on the optical path between the light source 35 and the objective lens 70 so that most of the light incident from the light source 35 passes toward the recording medium 30. The light reflected from the recording medium 30 and incident through the objective lens 70 is reflected to face the photodetecting unit 80. For example, as shown in FIG. 3, the optical path converting means 50 includes a polarizing beam splitter 51 for transmitting and reflecting incident light according to its polarization state and a wavelength plate 53 for converting polarized light of the incident light. Is done. Here, the wave plate 53 is preferably a quarter wave plate with respect to the light wavelength emitted from the light source 35.

Accordingly, one linearly polarized light of the light emitted from the light source 35 passes through the polarization beam splitter 51, and the transmitted light is converted into one circularly polarized light while passing through the wavelength plate 53. The circularly polarized light is reflected by the recording medium 30, is changed into another circularly polarized light, and is reincident to the wave plate 53. The re-incident light passes through the wavelength plate 53 and is converted into light of another linearly polarized light, which is reflected by the polarization beam splitter 51 to face the photodetectors 81 and 83.

On the other hand, it is preferable to further include a collimating lens 60 to focus the incident light on the optical path between the optical path conversion means 50 and the objective lens 70.

The focal length characteristic and arrangement of the objective lens 70 and the collimating lens 60 may change the divergent light of the paraxial region incident from the light source 35 into parallel light. The objective lens 70 is configured to focus incident incident parallel light to form an optical spot on the recording surface 31 of the recording medium 30.

As shown in FIG. 4, the main photodetector 81 detects an information reproduction signal of the recording surface 31 and receives a plurality of incident light and converts the incident light into an electrical signal independently. It is preferable that the partitions A, B, C, and D be made of.

The objective lens position detecting means is a means for detecting the amount of movement of the objective lens 70 so as to keep the objective lens 70 within a predetermined range, for example, 30 μm, from the optical axis during tracking.

The objective lens position detecting means may be provided with a flag sensor 90 for detecting the movement amount of the objective lens 70. In this case, the flag sensor 90 is provided with a light emitting source such as an LED inside the actuator cover for driving the objective lens, and detects the amount of movement of the objective lens by detecting light reflected and reflected from the light emitting source to the objective lens side. As is well known, the illustration and the detailed description are omitted.

Alternatively, a key servo technique may be used as the objective lens position detecting means. That is, as shown in FIG. 5, the division boundary line 181a of the main photodetector 181 for detecting the reproduction signal and the error signal is inclined at a predetermined angle with respect to the radial direction of the recording medium 30. In this case, a differential operator 185 may be provided to differential the detection signals of the partition plates A and D from the detection signals of the partition plates B and C. At this time, since the objective lens 70 is moved along the radial direction during tracking, the objective lens movement amount can be known from the output signal of the differential operator 185. Here, the solid line is an optical spot when the central axis of the objective lens 70 and the optical axis coincide, and the dotted line is an optical spot when the objective lens 70 is out of the optical axis.

The tilt detection means is a hologram lens disposed between the light source 35 and the polarizing beam splitter 51 to selectively diffract incident light so as to increase the amount of light reflected from the protective layer surface 33a of the recording medium 30. 40, an inclined light detector 83 for detecting the inclination of the recording medium 30 by receiving light reflected from the protective layer surface 33a, and an inclination detecting circuit unit for detecting the inclination of the recording medium 30 ( 100).

As illustrated in FIG. 6, the hologram lens 40 includes a first penetrating portion 41 through which light in a paraxial region of light incident from the light source 35 passes, and around the first penetrating portion 41. It is preferably formed of a second transmission portion 43 through which the light of the circular axis region of the incident light passes.

The first transmission part 41 is provided to, for example, transmit the light of the incident paraxial region in a straight line. The light in the paraxial region via the first transmission part 41 is formed as an optical spot on the recording surface 31 of the recording medium 30 by the collimating lens 60 and the objective lens 70. It is used to record and play back.

The second transmission part 43 includes, for example, a hologram pattern so as to diffract and deflect incident light by +1 or -1 order. In this case, as shown in FIG. 3, the second transmission part 43 is diffracted light focused by the collimating lens 60 and the objective lens 70 and then diverged to be incident on the protective layer surface 33a. Preferably, the focal point of the axial region light is positioned between the objective lens 70 and the recording medium 30. Here, the focal position of the circular axis region light may be formed to be located between the protective layer surface 33a and the recording surface 31. Here, the focal position as described above can be obtained by appropriately setting the pitch interval of the hologram pattern.

With the focal position as described above, the light in the paraxial region is incident and focused in parallel to the objective lens 70 to form a light spot on the recording surface 31, while the light in the circular axis region is the objective lens 70. Is incident obliquely to the light, is focused and collected at the focal point, then spreads and is incident on the protective layer surface 33a.

Therefore, the amount of light reflected by the protective layer surface 33a is much larger than when the hologram lens 40 as described above is not provided.

At this time, the light in the axial region is deflected while passing through the second transmission portion 43, and the axial region light reflected from the protective layer surface 33a and the paraxial region reflected by the recording surface 31 due to the difference in focal position. Since light has different divergence angles, light in the axial region is separated from light in the paraxial region, and is received by the inclined photodetector 83 provided at one side of the main photodetector 81.

The inclined light detector 83 divides the incident light into four separate plates (a, b, respectively) independently of the incident light so as to detect the tangential and radial inclinations of the track of the recording medium 30. c, d). At this time, the four-split plates a, b, c, d of the inclined photodetector 83 has a 2 × 2 matrix arrangement whose boundary line is parallel to the tangential direction and the radial direction of the recording medium 30 and counterclockwise. It is preferred to be arranged.

Here, the inclined photodetector 83 may include a plurality of dividers arranged in a tangential direction or a radial direction, and may be provided to detect a tangential or radial inclination of the recording medium 30.

The inclination detection circuit unit 100 includes a first operator 110 for calculating the inclination in the radial direction and a second operator 120 for calculating the inclination in the tangential direction.

For example, the detection signal of the partition plates (a, d) is input to the + input terminal of the first operator 110, and the detection signal of the partition plates (b, c) is input to the input terminal of the first operator 110 and is differential. To the + input terminal, the objective lens position signal is input from the flag sensor 90. Accordingly, the first operator 110 outputs a radial inclination signal in which the radial inclination signal offset generated by the movement of the objective lens is corrected.

For example, the detection signal of the partition plates (c, d) is input to the + input terminal of the second operator 120, and the detection signal of the partition plates (a, b) is input to the + input terminal of the second operator 120 to be differential. Therefore, the tangential tilt signal is output from the second operator 120.

At this time, if each of the dividers a, b, c, d and the detection signal are displayed with the same symbol, the tangential inclination signal becomes (a + d)-(b + c), and the radius inclination signal is offset corrected. Becomes (a + b)-(c + d).

Here, when the inclined photodetector is composed of two split plates arranged in a tangential or radial direction, the inclined detection circuit unit is provided with one calculator to detect a tangential or radial inclination.

On the other hand, reference numeral 65 denotes a reflection prism that reflects incident light, and reference numeral 75 denotes a detection lens that focuses the incident light and receives the light to the photodetectors 81 and 83.

The light in the relatively paraxial region emitted from the light source 35 of the optical pickup device having the above structure passes straight through the first transmission portion 41 of the hologram lens 40 and passes through the light path converting means 50. Incident on the collimating lens 60. The incident light is converted into parallel light by the collimating lens 60 and then focused by the objective lens 70 to form a light spot on the recording surface 31 of the recording medium 30. The light reflected from the recording surface 31 is received by the main photodetector 81 via the objective lens 70, the collimating lens 60 and the optical path changing means 50.

The light in the relatively axial region emitted from the light source 35 is deflected while diffracting the second transmission portion 43 of the hologram lens 40, and its propagation path is changed and then collimated via the light path converting means 50. Incident on the mating lens 60. This light is incident on the protective layer surface 33a of the recording medium 30 via the collimating lens 60 and the objective lens 70, and is reflected from the protective layer surface 33a, and then the objective lens 70, The light is received by the tilted light detector 83 via the collimating lens 60 and the light path converting means 50.

When the recording medium 30 is not inclined relative to the objective lens 70, the light spots received by the inclined photodetector 83 are divided into four split plates a and b, as shown in FIG. It is divided and received symmetrically with respect to, c, d, and the detected light amounts of the four-split plates a, b, c, d are approximately equal to each other. Therefore, the inclination detection signal a-b-c + d in the tangential direction and the inclination detection signal a + b-c-d in the radial direction are approximately zero.

When the recording medium 30 is inclined, for example, by one degree in the tangential direction, the light spot is biased toward the dividers a and d as shown in Fig. 8A, so that the inclination detection signal in the tangential direction, (a + d)- (b + c) represents a positive value. When the objective lens 70 is inclined and inclined according to the inclination detection signal of the recording medium 30, the light spot is moved toward the partition plates b and c as shown in FIG. ), And the tangential inclination detection signal (a + d)-(b + c) becomes zero. This means that there is no tangential inclination relative to the objective lens 70 of the recording medium 30. Similarly, by detecting an inclination signal in the radial direction of the recording medium 30 whose offset may be caused by the movement of the objective lens 70 during tracking, and controlling the inclination of the objective lens 70 according to the detection signal. The inclination of the radial direction of 30 is correct | amended.

As described above, the optical pickup apparatus according to the exemplary embodiment of the present invention detects an inclination amount of the recording medium 30 and actuates the objective lens 70 according to the inclination amount to record the objective lens 70. Correct the relative tilt of the medium 30. As described above, when the objective lens 70 and the recording medium 30 are relatively parallel to each other, even when the objective lens 70 having a relatively high number of apertures is employed, aberration may occur due to the inclination of the recording medium 30. In particular, coma aberration can be eliminated to obtain a stable recording / playback signal. In this case, the objective lens 70 maintains an on track and on focus state while being actuated to correct the inclination of the recording medium 30 and at the same time, the movement amount of the objective lens 70 is about 30 μm. Tracked while staying within

On the other hand, the hologram lens 40 of the optical pickup device according to an embodiment of the present invention is a hologram pattern for diffracting the incident light to +1 order or -1 order in the first transmission portion 41, the second transmission portion 43 It is also possible to be made to transmit the incident light straight.

In this case, similarly, the light in the paraxial region diffraction-transmitted through the first transmission portion 41 is focused on the recording surface 31 of the recording medium 30, reflected, and then detected by the main photodetector 81, and the second transmission portion Light in the axial region passing straight through 43 is reflected by the protective layer surface 33a of the recording medium 30 and then detected by the oblique light detector 83.

However, by moving the hologram lens 40 up, down, left and right, the influence of the focal position and aberration of the light spot formed on the recording surface 31 of the recording medium 30 can be changed. Therefore, an actuator (not shown) is installed in the hologram lens 40 to actuate the hologram lens 40 up, down, left, and right based on the tilt detection signal of the recording medium 30. It is also possible to automatically correct the coma aberration generated. In this case, it is not necessary to actuate the objective lens 70 to correct the inclination.

As another alternative, it is also possible to form a hologram pattern for diffracting incident light throughout the hologram lens 40. The hologram pattern is preferably formed so as to diffract most of the incident light in the 0th order and diffractively transmit some light in the + 1st or -1st order. In this case, the zeroth order diffracted light is used for recording and reproducing the information signal of the recording medium 30, and the + 1st or -1st order diffracted light is used for detecting the tilt of the recording medium 30.

9 is a view schematically showing the configuration of an optical pickup apparatus according to another embodiment of the present invention. Here, the same reference numerals as in FIG. 3 denote the same members having substantially the same functions. In the case of the light (paraxial region light in FIG. 3) used for recording and reproduction emitted from the light source 35, a part of the light is reflected from the protective layer surface 33a while being incident on the recording medium 30. The characteristic is that the inclination of the recording medium 30 is detected by detecting some reflected light.

In this case, since the light reflected from the protective layer surface 33a has a divergence angle greater than that reflected from the recording surface 31 of the recording medium 30, the recording surface 31 is viewed from the light receiving area of the photodetecting unit 180. Fall around the reflected light spot.

Therefore, in the present embodiment, as shown in FIG. 10, the inclination detection means includes inclination photodetectors 283, 284, 285, and 286, and inclination photodetectors disposed on both tangential and lateral sides of the main photodetector 81, respectively. And an inclination detection circuit unit 200 for detecting the inclination by receiving the detection signals of the 283, 284, 285 and 286 and the objective lens position signal. In this case, when the objective lens shift amount is detected using the key servo technique, the division boundary of the main photodetector is inclined at a predetermined angle with respect to the radial direction as shown in FIG. 5.

The inclined photodetectors 283, 284, 285, and 286 each have two split plates a, b, c, d, e, f, g and h. The inclination detection circuit 200 receives the detection signals of the split plates e and g and the split lens f and h, and differentially calculates the offset signals according to the shift of the objective lens. A first operator 210 for detecting the inclination and a second operator 220 for differentially calculating the detection signals of the dividers a and c and the dividers b and d to detect the inclination in the tangential direction. .

On the other hand, the inclination detection means preferably further comprises a hologram lens 140 on the optical path between the optical path conversion means 50 and the objective lens 70. The hologram lens 140 is formed around the first transmission portion 141 through which the light reflected from the recording surface 31 of the recording medium 30 passes, and the first transmission portion 141 to form the recording medium 30. It consists of a second transmission portion 143 through which most of the light reflected from the protective layer surface (33a) of the pass.

The first and second transmission parts 141 and 143 transmit most of the light incident from the light source 35 toward the straight line and selectively diffract light incident from the recording medium 30. For example, the first transmission part 141 is provided to transmit the light incident from the recording medium 30 straight, and the second transmission part 143 is +1 order of light incident from the recording medium 30. Or it is provided to diffraction through -1 order, or vice versa.

In this case, the light incident from the light source 35 is incident to the first transmission part 141.

Meanwhile, the collimating lens 160 is further provided on the optical path between the hologram lens 140 and the objective lens 70 so as to focus light incident from the light source 35 toward the hologram lens 140. It is preferable. The collimating lens 160 preferably has a size corresponding to approximately the first transmission portion 141.

Therefore, the light emitted from the light source 35 passes through the first transmission unit 141 and is then converted into parallel light by the collimating lens 160 and is focused on the recording medium 30 by the objective lens 70. Light reflected from the recording surface 31 is incident to the first transmission portion 141 via the collimating lens 160, and the light reflected from the protective layer surface 33a mostly passes the collimating lens 160. The light is incident directly to the second transmission part 143 without passing through.

In this case, since the second transmission portion 143 diffracts the light reflected from the protective layer surface 33a at a large divergence angle by +1 or -1 order, the light reflected from the protective layer surface 33a is recorded on the recording surface. Separated from the light reflected by 31 at a predetermined interval, the light is collected into an annular 190 having a predetermined width around the main photodetector 81, as shown in FIG.

When the hologram lens 140 and / or the collimating lens 160 are provided in this manner, the light reflected from the protective layer surface 33a can be collected into a predetermined region, so that the amount of light detected by the gradient photodetectors 283, 284, 285, and 286 is higher. Is increased.

According to the optical pickup apparatus as described above, when the recording medium 30 is not inclined, the annular light 190 reflected from the surface of the protective layer 33a is symmetrically received by each of the inclined photodetectors 283, 284, 285, and 286, and is tangent. The inclination detection signal value a-b + cd in the direction and the inclination detection signal value e-f + gh in the radial direction in which the offset according to the movement of the objective lens is corrected are approximately zero, respectively. If the recording medium 30 is inclined, for example, approximately 1 degree in the tangential direction, the annular light 190 is shifted toward one inclined photodetector 184 along the tangential direction, whereby the tangential detection signal value a -b + cd) becomes negative. Accordingly, the relative inclination between the objective lens 70 and the recording medium 30 may be adjusted by adjusting the inclination of the objective lens 70 according to the inclination detection signal value. The same is true when the recording medium 30 is inclined in the radial direction.

Here, the inclined photodetector may be provided on the outer circumferential side of the objective lens 70 facing the recording medium 30, and so on.

12 is a view schematically showing the configuration of an optical pickup apparatus according to another embodiment of the present invention. Here, the same reference numerals as in FIG. 3 denote members having substantially the same or similar functions. In addition, the recording medium 300 includes a protective layer 303 and a recording surface 301 as before.

Referring to the drawings, the optical pickup apparatus according to the present embodiment is provided between the first and second light sources 311 (321), the first and second light sources 311, 321 and the objective lens 70 for generating and emitting light. First light path converting means 340 disposed in the first and second light sources 311 and 321 to direct the light emitted from the first and second light sources 311 and 321 to the recording medium 300, and focus the incident light to the recording medium 300. Second optical path conversion means 313 disposed between the objective lens 70, the optical path between the first light source 311 and the first optical path converting means 340, and converting the traveling path of the incident light; A first light detector 315, a second light source 321, and a first light path converting means for receiving the light reflected from the recording medium 300 and converted by the second light path converting means 313; A third optical path converting means 323 disposed on an optical path between 340 and converting a traveling path of incident light, reflected by the recording medium 300, and transmitted by the third optical path converting means 323; A second photodetector 335 for receiving the converted light, an objective lens position detecting means for detecting an amount of movement of the objective lens 70, and optionally an inclination of the recording medium 300 in which an offset according to the movement of the objective lens is corrected It is configured to include a slope detection circuit 400 for detecting the.

The first and second light sources 311 and 321 are preferably provided to be compatible with HD-DVD and DVD. That is, the first light source 311 generates and emits light suitable for recording and / or reproducing HD-DVD, for example, light of approximately 400 nm wavelength region. The second light source 321 preferably generates and emits light suitable for recording and / or playing back DVDs, for example, light in the wavelength region of approximately 650 nm.

As the first light path converting means 340, for example, a mirror surface 340a which allows light of a wavelength region emitted from the first light source 311 to pass through and reflects light of the wavelength region emitted from the second light source 321. It is preferable to have a dichroic beam splitter in which) is formed. Here, the first optical path converting means 340 may include a conventional beam splitter.

The second optical path converting means 313 includes a beam splitter for transmitting and reflecting incident light. Alternatively, the second optical path converting means 313 may include a polarizing beam splitter (not shown) and a quarter wave plate (not shown) disposed between the polarizing beam splitter and the first optical path converting means 340. have.

The first photodetector 315 is emitted from the first light source 311, reflected from the recording medium 300, and then received light incident through the first and second optical path converting means 340 and 313. Each consists of a several partition plate which independently converts photoelectricity. Here, the first photodetector 315 has substantially the same structure as the main photodetectors 81 and 181 of FIGS. 4 and 5.

Most of the light incident from the second light source 321 is transmitted straight through the third light path converting means 323, and the light reflected from the recording medium 300 is diffracted by +1 or -1 order. The hologram member may be provided to face the second photodetector 325. In this case, the second light source 325 and the second photodetector 325 are disposed on the same substrate 327, and the second light source 321, the second photodetector 325, and the third optical path change are arranged. The means 323 may be integrally optically modulated (320).

Here, as shown in FIG. 13, the second photodetector 325 has a structure substantially the same as that of the oblique photodetector 83 of FIG. 4.

12 shows an example in which the flag sensor 90 is employed as the objective lens position detecting means, the key servo technique is arranged by arranging the first photodetector 315 together with the main photodetector 181 of FIG. It is also possible to be provided to detect the movement amount of the objective lens by using.

The inclination detection circuit unit 400 is selectively operated when the first light source 311 is operated to record and reproduce the information signal of the recording medium 300 to be emitted from the second light source 321 and the recording medium 300. The inclination of the recording medium 300 is detected by receiving the signal reflected from the protective layer surface 303a of the second photodetector 325 and the objective lens position signal. Here, the inclination detection circuit 400 is selectively operated only when the recording medium 300 of a specific format is employed to calculate the inclination of the recording medium 300. Same as in the example.

On the other hand, when the emission light wavelengths of the first and second light sources 311 and 321 are different from each other, the recording medium 300, for example, HD-DVD, which is recorded and reproduced by the optical pickup device having the above-described configuration, is a protective layer. As shown in FIG. 14, the surface facing the objective lens 70 of 303 transmits the light wavelength emitted from the first light source 311 and reflects the light wavelength emitted from the second light source 321. It is preferable to further provide a separation layer 305.

In this case, the light emitted from the first light source 311 at the time of HD-DVD recording reproduction passes through the color light separation layer 305 and is irradiated to the recording surface 301 while the light emitted from the second light source 321 The light is reflected by the color separation layer 305 and detected by the second photodetector 325. Therefore, since the amount of light reflected from the surface of the recording medium 300 can be further increased, more accurate detection can be achieved.

The optical pickup apparatus having the above configuration records and reproduces the information signal of the recording medium 300 and detects the tilt of the recording medium 300 as follows.

First, when recording and reproducing HD-DVD, not only the first and second light sources 311 and 321, but also the inclination detection circuit unit 400 are selectively operated. The light emitted from the first light source 311 passes through the second and first light path converting means 313 and 340 sequentially and is focused by the objective lens 70 to light spot the recording surface of the HD-DVD. Is concluded. The light reflected from this recording surface is reflected by the second optical path converting means 313 via the objective lens 70 and the first optical path converting means 340 and then received by the first light detector 315. The first photodetector 315 detects an information reproduction signal of the HD-DVD and / or an error signal.

The light emitted from the second light source 321 passes through the third light path converting means 323 and is reflected by the first light path converting means 340 and then irradiated onto the surface of the protective layer by the objective lens 70. It is reflected by this protective layer surface (color light separation layer, if there is a color light separation layer). The reflected light is reflected by the first light path converting means 340 via the objective lens 70 and then diffracted by the third light path converting means 323 and received by the second light detector 325.

The inclination detection circuit unit 400 receives the detection signal of the second photodetector 325 and the object lens position signal to detect the inclination of the radial direction in which the offset according to the movement of the objective lens 70 during tracking is corrected. At the same time, when the second photodetector 325 and the inclination detection circuit unit 400 are provided to detect the inclination in the tangential direction, the inclination in the tangential direction is detected.

On the other hand, when recording and reproducing a DVD, the first light source 311 and the inclination detection circuit unit 400 are not operated, and only the second light source 321 is operated.

The light emitted from the second light source 321 is irradiated onto the recording surface of the DVD, reflected by the recording surface, and then received by the second photodetector 325. In this case, the second photodetector 325 detects an information reproduction signal and / or an error signal of the DVD.

In the above, the optical pickup apparatus of FIG. 12 may adopt HD-DVD and DVD, and when adopting HD-DVD, it is limited to detecting an information signal and / or an error signal of the HD-DVD and simultaneously detecting tilt. Although described and illustrated, the reverse is also possible.

In addition, an inclination circuit detector (not shown) is further provided to receive the detection signal of the first photodetector 311 and the objective lens position signal, so that the detection signal of the second photodetector 325 is detected when recording and reproducing the HD-DVD. The inclination of the HD-DVD can be detected using the detection signal, and the inclination of the DVD can be detected using the detection signal of the first photodetector 315 during DVD recording and reproduction.

In addition, most optical elements including one light source and a corresponding photodetector are provided to be compatible with HD-DVDs and DVDs, and other light sources and corresponding photodetectors and tilt detection circuits are provided in the type of the recording medium 300. Regardless of the inclination of the recording medium 300 may be provided to operate as necessary.

In addition, the optical pickup apparatus as described above may be applied to CDs and DVDs in the same manner, and may be applied to CDs, DVDs, and HD-DVDs when the protective layer thickness of the HD-DVD is determined to the same standard as the DVD. .

In addition, a tilt detection circuit unit (not shown) may be further provided to detect the tilt by receiving the detection signal of the first photodetector 315 and the objective lens position signal. In this case, while the light emitted from the first light source 311 records and reproduces the information signal of the recording medium 300, the light emitted from the second light source 321 may incline the recording medium 300 as necessary. It can be used for detection and vice versa depending on the recording medium 300.

The optical pickup apparatus according to the present invention, which has been described through the above embodiments, is reflected by the protective layer surfaces 33a and 303a of the recording medium 30 and 300 (in the case of the recording medium including the color separation layer, the color separation layer 305). Since the inclination of the recording mediums 30 and 300 is detected by calculating the light detection signal and the object lens position signal, the inclination signal in which the offset due to the movement of the objective lens 70 is corrected can be detected, and the objective lens 70 and the recording are detected. Inclination can be detected even when the relative inclination angle between the media 30,300 is inclined relatively largely by 1 degree or more.

Further, the optical pickup apparatus as described above can record and reproduce the information signal and detect the inclination of the recording medium 30,300 regardless of the thickness of the protective layers 33,303 of the recording medium 30,300. That is, not only the CD having a thickness of 1.2 mm and a DVD having a thickness of 0.6 mm, but also an HD-DVD which is expected to be specified to a thickness of 0.6 mm or thinner, for example, 0.1 mm in the future, 70 and the relative inclination between the recording medium 30, 300 can be detected.

According to the present invention as described above, since the inclination of the recording medium is detected by using the light emitted from the light source of the optical pickup device and reflected from the surface of the protective layer of the recording medium without a separate tilt sensor, the number of parts is reduced compared to the conventional structure Is simplified, and the radial inclination signal with the offset which can be generated due to the movement of the objective lens during tracking can be detected, so that more accurate inclination signal detection is possible.

Claims (22)

An optical pickup apparatus for recording and reproducing an information signal of a recording medium having a recording surface on which an information signal is recorded and a protective layer for protecting the recording surface on a side to which light of the recording surface is incident. A light source for generating and emitting light; Optical path converting means for converting a traveling path of the incident light; An objective lens for focusing light incident from the light source toward a recording medium; A main photodetector, which is reflected from the recording surface of the recording medium and receives the light incident through the objective lens and the optical path converting means to detect an information signal and / or an error signal; Objective lens position detecting means for detecting a movement amount of the objective lens; And The objective lens of the recording medium having the offset corrected by the movement of the objective lens by calculating a signal received from the light source and received from the protective layer surface of the recording medium and a signal input from the objective lens position detecting means And an inclination detection means for detecting an inclination relative to the optical pickup device. According to claim 1, wherein the inclination detection means, A plurality of partition plates which are reflected on the surface of the protective layer and which receive light incident through the objective lens and the optical path converting means, and which are independently photoelectrically converted are arranged in the tangential direction and / or the radial direction of the recording medium. Inclined photodetector; And And an inclination detection circuit unit configured to detect the inclination of the recording medium in which an offset according to the movement of the objective lens is corrected by receiving the detection signal of each partition plate of the inclination light detector and the objective lens position signal of the objective lens position detecting means. Optical pickup device characterized in that. According to claim 2, The inclination detection means, And a hologram lens disposed on an optical path between the light source and the optical path converting means, to selectively diffract and transmit the light incident from the light source to increase the amount of light reflected from the surface of the recording medium protective layer. Optical pickup device. The method of claim 3, wherein the hologram lens, A first transmission part through which light in a relatively paraxial region is used for recording and reproducing information signals among light incident from the light source, and a first periphery formed around the first transmission part to pass light in a relatively circular region among the incident light beams; 2. The optical pickup apparatus of claim 1, wherein one of the first and second transmission parts transmits incident light in a straight line, and the other diffracts the incident light in +1 order or -1 order. The optical pickup apparatus of claim 4, wherein the hologram lens is actuated according to the tilt detection signal of the recording medium of the tilting photodetector to automatically correct the coma aberration caused by the tilting of the recording medium. The tilt detector of claim 3 or 4, wherein Four partition plates (a, b, c, d) positioned at one side of the main photodetector and whose boundaries are arranged counterclockwise with a 2x2 matrix arrangement parallel to the tangential and radial directions of the recording medium; Made of The inclination detection circuit unit, The detection signal of the partition plates a and d and the detection signal of the partition plates b and c are inputted to different input terminals to be differentially input, and the objective lens position signal is input to the one input terminal. A first operator for outputting a radial inclination signal in which the offset is corrected; And And a second operator for differentially detecting the detection signals of the partition plates (a and b) and the detection signals of the partition plates (c and d) and outputting a tangential signal in a tangential direction. The tilt detector of claim 3 or 4, wherein Located at one side of the main photodetector, the boundary line is composed of two partition plates parallel to the radial direction of the recording medium, The inclination detection circuit unit, The detection signals of the two split plates are inputted to different input terminals to be differential, and the objective lens position signal is input to the one input terminal, and a calculator for outputting a radial inclination signal in which an offset according to the movement of the objective lens is corrected is provided. Optical pickup device characterized in that. The tilt detector of claim 2, wherein And at least one side of the main photodetector provided with a plurality of divider plates disposed in a tangential and / or radial direction of the recording medium to detect light reflected from the surface of the protective layer. The tilt detection means according to claim 2 or 8, It further comprises a hologram lens disposed on the optical path between the optical path conversion means and the objective lens, The hologram lens includes a first transmission part provided so that most of the passing light is reflected light from the recording surface of the recording medium, and a light passing through most of the light reflected from the surface of the protective layer of the recording medium. A second transmission part, wherein one of the first and second transmission parts transmits light incident from the recording medium side, and the other diffracts the light incident from the recording medium side by +1 order or -1 order. Optical pickup device characterized in that. The optical pickup apparatus according to any one of claims 1 to 4 and 8, wherein the objective lens position detecting means is a flag sensor that detects an objective lens shift amount. The first photodetector of claim 1, wherein the main photodetector independently photoelectrically converts the boundary line of the main photodetector at an angle with respect to the radial direction of the recording medium. And a second light receiving region, The objective lens position detecting means, And a differential operator which detects a center error signal by differentially detecting detection signals of the first and second light receiving regions. An optical pickup apparatus for recording and reproducing an information signal of a recording medium having a recording surface on which an information signal is recorded and a protective layer for protecting the recording surface on a side to which light of the recording surface is incident. First and second light sources for generating and emitting light; First light path converting means for directing the light emitted from the first and second light sources to the recording medium; An objective lens for focusing incident light toward the recording medium; Second optical path converting means disposed on an optical path between the first light source and the first optical path converting means and converting a traveling path of incident light; A first photodetector configured to receive light reflected from the recording medium and converted by the second optical path converting means; Third optical path converting means disposed on an optical path between the second light source and the first optical path converting means to convert a traveling path of the incident light; A second photodetector configured to receive light reflected from the recording medium and converted by the third optical path converting means; Objective lens position detecting means for detecting a movement amount of the objective lens; And Receiving the detection signal of the first or second photodetector and the objective lens position signal of the objective lens position detecting means to receive the light emitted from the first or second light source and reflected from the surface of the protective layer of the recording medium And an inclination detection circuit unit for detecting an inclination of the recording medium whose offset according to the movement of the objective lens is corrected. 13. The light source of claim 12, wherein one of the first and second light sources irradiates light on the recording surface of the recording medium to record and reproduce the information signal on the recording surface. And the other light source irradiates light on the surface of the protective layer of the recording medium, and detects the light reflected from the surface of the protective layer by a photodetector corresponding thereto to detect the inclination of the recording medium. 13. The method of claim 12, wherein the first light source generates and outputs light suitable for recording and / or playing back an HD-DVD, and the second light source generates and outputs light suitable for recording and / or playing back a DVD. An optical pickup device, characterized in that the DVD and DVD to be compatible with the adoption. 15. The method of claim 14, wherein the first and second light sources are reflected from the surface of the protective layer of the DVD or HD-DVD and received by the first or second photodetector to detect the detected signal is selectively input to the inclination detection circuit section. And an inclination of the DVD or the HD-DVD. The optical pickup apparatus according to any one of claims 12 to 15, wherein the first and second light sources generate and emit light of different wavelength regions. 17. The recording medium of claim 16, wherein the recording medium of a predetermined format to be recorded and / or reproduced passes light on one wavelength region emitted from the first and second light sources on the surface of the protective layer, and reflects light of another wavelength region. An optical pickup apparatus comprising a color light separation layer. The method of claim 12, wherein the first or second photodetector, The boundary line is composed of four partition plates (a, b, c, d) arranged in a counterclockwise direction with a 2x2 matrix arrangement parallel to the tangential and radial directions of the recording medium, The inclination detection circuit unit, The detection signal of the partition plates a and d and the detection signal of the partition plates b and c are inputted to different input terminals to be differentially input, and the objective lens position signal is input to the one input terminal. A first operator for outputting a radial inclination signal with offset corrected; And And a second operator configured to differentially detect the detection signals of the partition plates (a and b) and the detection signals of the partition plates (c and d) to output a tangential inclination signal. The method of claim 12, wherein the first or second photodetector, The boundary line is composed of two partition plates parallel to the radial direction of the recording medium, The inclination detection circuit unit, And a calculator for differentially detecting the detection signals of the two split plates and inputting the objective lens position signal to the one input terminal and outputting a radial inclination signal in which an offset according to the movement of the objective lens is corrected. Optical pickup device characterized in that. 20. An optical pickup apparatus according to any one of claims 12 to 15, 18 and 19, wherein said objective lens position detecting means is a flag sensor for detecting an amount of objective lens movement. 20. The optical detector according to any one of claims 12 to 15, 18 and 19, wherein one optical detector for detecting a reproduction signal and an error signal of a recording medium of a predetermined format among the first and second photodetectors is used as an optical axis. A boundary line of which is inclined by a predetermined angle with respect to the radial direction of the recording medium, and includes first and second light receiving regions each independently photoelectrically converting, The objective lens position detecting means, And a differential operator which detects a center error signal by differentially detecting detection signals of the first and second light receiving regions. 20. The light beam according to any one of claims 12 to 15, 18, and 19, wherein the third light path converting means transmits most of the light incident from the second light source side straight and enters from the recording medium side. Is mostly a hologram member that diffracts and transmits in +1 or -1 order, And the second light source, the second photodetector, and the hologram member form an integrated optical module.